Antibodies. For an naive B cell it is generally IgM and IgD. An activated B cell will express IgA, IgE or IgG after it goes through isotype switching.
Yes the antigen binding sites on the Cell determine the antigen which it bonds to and differentiates using histocompatabilty markers.
IgM
glycoproteins
Lock and Key to the Nth Degree. When any one of 'very many' intercellular 'blood borne' Activating Factors finds & fits-to a Cell Surface Receptor, this causes conformational changes to the...